This document describes a patent for a device used to de-scale the bores of tubes. The device consists of a helical coil wire cutting section with an extended central stem. A washer is connected to the free end of the stem to make fluid-tight contact with the tube. The pitch of the helical coil decreases toward the washer to prevent rifling of the tube bore during use. The device is passed through the tube bore with fluid pressure to de-scale the inside of the tube.

1. * GB780093 (A)
Description: GB780093 (A) ? 1957-07-31
Devices for de-scaling the bores of tubes
Description of GB780093 (A)
PATENT SPECIFICATION
-' Date of filing Complete Specification: May 9, 1956.
Application Date: Feb. 17, 1955. No. 4730/55.
Complete Specification Published: July 31, 1957,
Index at acceptance:-Class 99(2), A1B(3; 4).
International Classification;-FO6lo COMIPLETE SPECIFICATION
Devices for De-Scaling the Bores of Tubes We, GORDONBowYEi, a British
Subject, of 32, Lazy Hill Road, Aldridge, near Walsall, Staffordshire,
and ALEC MACLEOD, a British Subject, of 66, Charlemont Road, Walsall,
Staffordshire, do hereby declare the invention, for which we pray that
a patent may be granted to us, and the method by which it is to be
performed, to be particularly described in and by the following
statement:-
This invention relates to devices for de-scaling the bores of tubes,
more particularly the condenser tubes in power station installations,
such devices being of the kind which are adapted to be driven through
the bore of the tube by fluid pressure and which are generally known
as bullets.
The object of the invention is to provide a de-scaling device of this
kind in a convenient form.
A de-scaling device according to the invention comprises a cutting
section formed as a helical coil of wire one end of which is extended
centrally through the coil to form an integral axial stem, and a
washer or like member connected to the free end of the stem and
adapted to make fluid tight contact with the tube to be de-scaled.
In the accompanying drawings Figure 1 is a side view, and Figure 2 is
an end view of an example of a de-scaling device in accordance with
the invention.
The cutting section 3 of the device is formed from steel or other hard
wire of square or other convenient cross-seftion which is coiled to

2. form a cylindrical helix. One end of this helical coil is extended
centrally through the coil to form an integral axial stem 4, and to
the free end of this stem is secured a boss 5 having a peripheral
groove in which is mounted an annular rubber, or other washer 6
adapted to make fluid tight contact with the bore of the tube to be
de-scaled.
The pitch of the helical coil 3 may be constant, 780093 but desirably
as shown decreases towards the washer 6. By this means any tendency
for the device to rifle the bore of the tube during use is 45 obviated
or minimised. The external diameter of the cutting section is
desirably very slightly less than the bore of the tube to be
de-scaled, and conveniently may first be coiled to a diameter greater
than that required and ground 50 or lapped on a centreless grinding
machine.
In use the device is adapted to be passed through the bore of the tube
with the washer 6 rearmost. Thus, since the cutting section is
attached to the stem at its leading end, in the 55 event of the coil
meeting excessive resistance it will be extended axially in the manner
of a coil spring to reduce the diameter of the coil.
In de-scaling a tube it is preferable to pass two devices as described
through the bore in 60 succession, the first or pilot device being of
slightly smaller diameter than the second or finishing device. When a
finishing device has become worn this can then be re-ground to a
smaller diameter for use as a pilot device. 65
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